//下载图片 imgUrl:图片的地址 name:图片的名字
export function  downloadImage(imgUrl,name){
	let  image = new Image();
	// 解决跨域 Canvas 污染问题
	image.setAttribute("crossOrigin", "anonymous");
	image.onload = function() {
		let canvas = document.createElement("canvas");
		canvas.width = image.width;
		canvas.height = image.height;
		let  context = canvas.getContext("2d");
		context.drawImage(image, 0, 0, image.width, image.height);
		let url = canvas.toDataURL("image/png"); //得到图片的base64编码数据
		let  a = document.createElement("a"); // 生成一个a元素
		let event = new MouseEvent("click"); // 创建一个单击事件
		a.download = name || "photo"; // 设置图片名称
		a.href = url; // 将生成的URL设置为a.href属性
		a.dispatchEvent(event); // 触发a的单击事件
	};
	//图片的路径
	image.src = imgUrl;
}